It is known in the prior art to utilize both voidfree elastomer fillers, as well as those of prescribed porosity, to completely fill the core of a tire. Such an elastomeric filler is normally derived from a prepolymer of an organic polyisocyanate and polyether or a polyester. In addition to the complete filling of a tire core as heretofore described, various sealant compositions are taught in the art, for example, one-shot recipes containing essentially butyl rubber, active carbon and sulfur as the main sealant ingredients.
It is known to be optional, for example, to utilize a phenol formaldehyde resin to effect a thermosetting cure of the inner portion of a penetrating nail to fix said nail as it has pierced the tire casing and the sealant composition applied therein. It is further known in the art to utilize a self-sealing single-component composition in combination with the inner surface of a pneumatic tire, such a composition containing a partially cured butyl rubber in combination with a curing agent and an auxiliary curing agent such as black iron oxide. Numerous other single-component sealant compositions are known in the art and require a controlled balance of properties to be maintained after application of the sealant to the inner surface of a pneumatic tire, primarily in the adjacent tread and sidewall portions.
U.S. Pat. No. 3,981,342 is directed to a puncture sealing composition for pneumatic tires, said composition containing a mixture of high and low molecular weight elastomers, the latter being present in an amount more than 50%, partial curing of the mixture maintains the flow, rigidity and strength of the total mix and functions effectively as a sealant; examples of high molecular weight elastomers disclosed include polyisoprene, polybutadiene, butyl rubbers and EPDM elastomer types. Examples of low molecular elastomers that are of a molecular weight less than 50,000 include liquid polybutene, liquid EPDM and liquid butyl rubber.
U.S. Pat. No. 4,032,500 is directed to a curable polyurethane sealant two-component system, each composition component being storage-stable and containing medium process oil-extended low molecular weight uncured butyl rubber which remains uncured; the components are mixed in a volume ratio of about 1.0 to 1.0. The first component contains NCO terminated prepolymer and the second component contains the low molecular weight polyol reactant for said prepolymer.
U.S. Pat. No. 4,116,895 is directed to an emulsified puncture sealant composition for a tubeless pneumatic tire, said composition comprising a butyl rubber emulsion, at least one saturated hydrocarbon polymer emulsion, a cross-linking agent for the rubber and a cross-linking activator. This puncture sealant composition can also include at least one additional rubber component selected from the group consisting of diene type unsaturated hydrocarbon polymer emulsions and a natural rubber latex, this being in addition to the other specified components.